Cloning of the hot and cold thermal receptors has advanced the understanding of the molecular basis of thermal sensation. Two important remaining questions to be addressed are the identification of additional thermal receptor genes and the elucidation of the mechanism(s) that enable the receptor proteins to alter gating properties in response to changes in temperature. Existing technologies for studying thermal response employ devices that elicit temperature changes, under feed back control, at rates less than 4 degrees C/sec. These rates are generally inadequate for characterizing distinct temperature responses of individual sensory neurons and for elucidating kinetic components of conformational changes in response to temperature. The goal of this project is to engineer a device that can generate much faster temperature changes, under feedback control, than are attainable with current commercial devices. This device will use a proprietary technology that enables rapid temperature switching by rapidly switching solutions applied from a focal application device. The output of the device will be applied to excised membrane patches under patch clamp, or to individual cells voltage-clamped by discontinuous single-electrode voltage clamp or patch clamp. Other applications of this device may also be possible.